Thus, primary EO771 and EO771.LMB tumours were analysed by immunohistochemistry (Fig. 2) for markers of the luminal A/B subtypes (ERα, ERβ, PR), the HER2 subtype (Erb-b2/Neu) and the basal-like subtype (KRT5/6, EGFR) and compared to 67NR and 4T1.2 tumours. Here, ESR1 is linked to neoplasm.